The z-transform of (( frac{1}{4})^n ) (u[n] u[n-5]) is __________

• A. ( frac{z^5 0.25^5}{z^4 (z-0.25)} ), z>0.25
• B. ( frac{z^5 0.25^5}{z^4 (z-0.25)} ), z>0
• C. ( frac{z^5 0.25^5}{z^3 (z-0.25)} ), z<0.25
• D. ( frac{z^5 0.25^5}{z^4 (z-0.25)} ), all z